"Cannot calculate the route" message

[tombarrington]

Greetings,

I've seen this message mentioned in several past posts but I'm still looking for the reason it pops up and for potential solutions.



This one occurred after deviating from the planned route to take a different way home. I received numerous u-turn instructions before this message and then the navigation quit. Since there were several perfectly valid alternate routes home I'm surprised the Zumo did not recalculate and give me one of them. From what I've read, it may trigger this error after a certain number of u-turn instructions and I certainly had a lot of them. There were no shaping points between where I left the route and where I would rejoin. This has also happened when pulling off a route just slightly, such as into a parking lot. In those cases, restarting the route seems to work fine.

This route was created in BaseCamp using City Navigator North America NT 2024.1, same as the device. Routing is set for faster time and avoidances are unchecked. The Zumo XT software version is 6.50. Garmin technical support, usually good, could not come up with an answer and told me to use Explore. Not happening.

Has anyone figured this out?

Tom

[sussamb]

Impossible to say without loads more detail. Never seen it on any of my Garmin units.

[rbentnail]

I see this all the time on my XT. To me, it seems like it picks a point to route to then is never able to change it's choice if you deviate from that chosen route. I got used to the 595 model being able to adapt to a new entry point when I deviate, this is extremely helpful when starting b/c I could make my start point about 4 miles out of town and wherever I went- breakfast, gas station, convenience store, back to the motel for a dump- the 595 would always, without fail, adapt its route to get to my start point. The XT will NOT do this, it gives a few u-turns then the message and termination of the route. This is one of the annoying quirks of the XT that I've never found a reliable workaround for. I mostly just call it a stupid s.o.b. and restart the route. One thing that does seem to help is to have a route with multiple VIA points in the beginning so that skipping one forces the XT to want to go to the next one. SHAPING points don't seem to help in this workaround tho. And it's seems inconsistent sometimes working & sometimes not despite me (I think) doing everything exactly the same.

[Peobody]

And it's seems inconsistent sometimes working & sometimes not despite me (I think) doing everything exactly the same.

My experience too!

I disagree with skipping a Via point though, especially early in a route. The resulting recalc of the remainder of the route more often than not results in a changed route.

[tombarrington]

I'm partial to shaping points as I understand skipping a via point will cause the Zumo to recalculate the rest of the route, ignoring any subsequent shaping or via points. For my rides that would almost certainly result in a different route.

Garmin claims they can't reproduce this problem but I expect it's been reported many times.

[Peobody]

I understand skipping a via point will cause the Zumo to recalculate the rest of the route, ignoring any subsequent shaping or via points

This is not the case. It includes subsequent waypoints in its recalc but as we know, a route calculation by the XT can be very different than by a route creation app like BaseCamp, especially with the XT's propensity for routing over faster roads regardless of additional time or distance.

[tombarrington]

Thanks for the clarification. So what's the best response to the "Cannot calculate the route" message? Just restart the trip?

[Peobody]

Restarting the route is good if you intend to follow it but is fruitless if you have decided that you want a different way. in that case, using "Where to" and selecting the ending waypoint of the route may be the best option.

[tombarrington]

I use the Zumo almost exclusively for all-day and multi-day trips. I almost never enter a location and let it calculate unless it's a restaurant or something. The "cannot calculate" thing is a PITA and I expect better from Garmin.

[Stu]

I have had this once or twice and it sounds like it's related to this viewtopic.php?t=2030

It sounds like it's got stuck in the classic U turn fault instead of rerouting you

I would report this to garmin in the hope that we can get it fixed